As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 2 ENGINE FIRE DETECTION LOOP A INOPERATIVE. ACFT GROUNDED. RETURNED NR 2 ENGINE OVERHEAT DETECTOR SWITCH ON ENGINE AND APU FIRE CONTROL PANEL BACK TO THE NORMAL POSITION. PERFORMED BITE OF ENGINE AND APU FIRE DETECTION MODULE IAW FIM 26-10-801. FOUND AN ENGINE FAN UPPER A LOOP FAULT. REMOVED AND REPLACED FAN UPPER A AND B DETECTOR ASSEMBIES IAW AMM 26-11-01. BITE AND OPS CHECKED GOOD IAW FIM 26-10 TASK 801.